Known in the art are facing panels for walls in buildings and constructions in general, formed by two flat metal sheets joined together, one of which forms the internal side of the panel while the other forms the outer side, between which sheets is a chamber filled with material of a heat-insulating nature.
This type of flat panels for covering the outer walls of a building or construction is unsuitable for use as a roof or roofing, for the seals between the elements thereof lack sufficient watertightness.
Another type of roof currently used is made up of channeled panels, that is, panels with their outer side provided with longitudinal projections or drawings, which alternate with channels. These roofs have a disadvantage of an aesthetic order, owing to the presence of the projections, and furthermore their attachment to the support beams or purlins is implemented by means of threaded stems which pass through he panels, the heads of these stems being left on the outer side of the panels, which means that they deteriorate easily through the action of atmospheric agents. Similarly, the joints between the panels, formed by weather strips or beads, can suffer wear over time, therefore allowing possible infiltration of rainwater.
Also known are roofing panels of the type described above, which, once placed on the support structure, are joined to each other by means of a flanging operation, which consists in bending together, one around the other, two longitudinal edges of the sheets which compose the two sides of the panel, in order to achieve their watertight joining together. This operation is carried out once the sheets have been fitted on the support structure, using a portable machine which is complex to operate, so that fitting of this type of roofing is slow and costly.